4: Epithelial Tissue

Question 1

What are the different polarities in epithelium?

Answer 1

• apical surface (free facing)
• basolateral: the sides of opposite of apical surface.
• lateral: the sides

Question 2

The Germ Layers are?

Answer 2

• ectoderm: skin and glands of epidermis
• endoderm: GI tract lining and glands
• mesoderm: bowman’s capsule, blood vessel linings, mesothelium.

Question 3

What makes up the basement membrane?

Answer 3

• reticular lamina: underlying connective tissue.

- basal lamina: next to epithelial.

Question 4

Basal lamina

Answer 4

• consist of collagen IV, glycoprotein, and PAS+.

- essential for differentiation during embryogenesis

Question 5

Reticular lamina

Answer 5

-form from glycoprotein, argyrophilic fiber (able to be stained with silver)

Question 6

What is the basement membrane used for?

Answer 6

• barrier
• platform for embryogenesis/regeneration.
• stabilize tissue shapes.

Question 7

What is Epithelial tissue?

Answer 7

Forms part of excretory and secretory glands, while lining cavities and surfaces of the body, and is therefore innervated.

Question 8

Simple Squamous Epithelium

Answer 8

-major role in protection that lines tubular and are good at diffusion and filtration.

Question 9

Simple Cuboidal Epithelium

Answer 9

• Lines ovary, kidney tubules.

- Contains a brush border (microvilli), known to form large tubule structures.

Question 10

Simple Columnar Epithelium

Answer 10

• Column in shape.
• Excretion and secretion
• ciliated: located in uterin tube, Upper Resp. tract sinus.
• non-ciliated: gallbladder, excretory duct glands.

Question 11

Stratified Squamous Epithelium

Answer 11

• heavy keratinization in epidermis with CT papillae. Cornea (no nucleus)
• light keratinization: esophagus, vaginal lining, tongue. (presence of nucleus)

Question 12

Stratified Cuboidal Epithelia

Answer 12

• male urethra, anal mucosa

- rare to find

Question 13

Stratified columnar epithelium

Answer 13

• pharynx, sweat gland duct, epiglottis.

- rare

Question 14

Psuedostratified Epithelium

Answer 14

-appears that not every cell is in contact with BM, when it actually is.

Question 15

Laminin

Answer 15

• major component for basal lamina.
• alpha, beta, gamma strands
• binds integrin, collagen IV, enactin, proteoglycans.

Question 16

Fibronectin

Answer 16

• bind with heparin, integrin, collagen, fibrin
• Cellular: produces fibroblasts, ECM.
• Plasma: hepatocytes secrete into blood stream

Question 17

Describe major CAMs

Answer 17

• cadherins (Ca dependent)
• selectins (Ca dependent)
• integrins (Ca independent)
• immunoglobulin superfamily molecules (Ca independent)

Question 18

What are the epithelial tissue structure?

Answer 18

• no blood vessel
• display apical surface
• small intercellular matrix

Question 19

What are the groups of cadherins?

Answer 19

• classical

- non classical

Question 20

Classical cadherins are made up of?

Answer 20

• Epithelial cells ( have HVA binding site.)
• Nerve cells
• Placental tissue

Question 21

What are groupings within selectin CAMs?

Answer 21

• Platelet
• Endothelial
• Leukocytes

Question 22

Describe what an Integrin is. (units, binding sequence…)

Answer 22

• glycoprotein involved with ECM interactions
• alpha subunit: disulfide bonds of two chains.
• beta subunit: has cysteine rich areas for binding with actin.
• Binding site: RGD

Question 23

Where can lightly-keratinized squamous epithelium be found?

Answer 23

Vaginal Epithelium

Question 24

Not common stratified cuboidal epithelium may be found where?

Answer 24

male urethra

anal mucose

Question 25

What are urothelium?

Answer 25

transitional eipthelium of the urinary tract

Question 26

What role does catenin play in cadherins?

Answer 26

1) Directly link to filamentous actin. 2)interact w/ regulatory molec. of actin cytoskeleton. 3) control adhesive state

Question 27

What are selectins used for and describe this process.

Answer 27

movement of leukocytes towards tissue. Tissue signals for help, by activating the selectin w/ Ca. Slows the leukocyte as carbohydrate ligands bind to activated selectins. The leukocyte migrates out of blood stream.

Question 28

Where are immunoglobulin superfamily members from?

Answer 28

mRNA. | play important role of homing process, during inflammation.

Question 29

What forms an Integrin?

Answer 29

1)binding of alpha/beta subunits. 2) transmembrane units that connect to actin via complexes. 3) RGD aa sequence on B-unit connects actin to the fibronectin/laminin.

Question 30

Hemidesmosomes

Answer 30

Anchor basal domain to the basal lamina. Increase stability by linking intermediate filaments with basal lamina, by integrins.

Question 31

What is a gap junction, and its characteristics?

Answer 31

used for rapid ion exchange, communication of cells. Utilize a cylinder of 6 connexin molecules. (i.e. cardiac cells for rapid electrical relay)

Question 32

What is the result of a improper E-cadheren?

Answer 32

1) Indicates metastisis. 2) loss of cell-to-cell adhesion.

Question 33

Zonula Adherens

Answer 33

1) found below tight junctions. 2) Use cadherens to interact with catenins.

Question 34

Macula Adherens

Answer 34

1) provide rigidity to cell. 2) separated by wide intercellular space. 3) form cell-cell bond with cadherens.

Question 35

Integrins

Answer 35

1) directly interact w/ laminin and fibronectin.

Question 36

PAS positive structures

Answer 36

1)basement membrane. 2) collagens. 3)glycocalyx. 4) glycoprotein hormones.

Question 37

What proteins interact with cadherins and actin?

Answer 37

1. alpha actinin 2. vinculin 3. formin-1 4. catenins: alpha, beta, p120

Question 38

Proteins involved with integrin binding to actin?

Answer 38

1. talin 2. vinculin. 3. kindlin 4. alpha-actinin 5. IPP complex

Question 39

Microtubule inhibiting factors are?

Answer 39

1. colchicines 2. colcemid 3. vincristine 4. cinblastin 5. all inhibit tubulin dimer formation

Question 40

Taxol

Answer 40

-microtubule stabilizing factor

Question 41

intermediatte filaments

Answer 41

- provide cytoplasmic network. | - type I, II, III, IV, V

Question 42

Type I Int fil.

Answer 42

I and II are acid and basic int. filaments.

Question 43

Type III int. fila.

Answer 43

- self assembling - Peripherin - Vimentin - Glial fibrillary - Desmin